The invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing charge enhancing additives, which impart or assist in imparting a positive charge to the toner resin particles and enable toners with rapid admix characteristics. In one embodiment, there are provided in accordance with the present invention toner compositions comprised of resin particles, pigment particles, and certain quaternary ammonium sulfates, including preferably bis or di distearyldimethylammoniumsulfate [DD'A).sub.2 SO.sub.4)] wherein D is distearyl and D' is dimethyl, charge enhancing additives, which additives enable, for example, toners with rapid admix of less than about 15 seconds in some embodiments, extended developer life, stable electrical properties, high image print quality with substantially no background deposits, and compatibility with fuser rolls including Viton fuser rolls. With further regard to admix, the toners of the present invention in an embodiment thereof had excellent admix of times less than or equal to 15 seconds as determined by a charge spectrograph. The aforementioned toner compositions usually contain pigment particles comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magnenta, yellow, blue, green, red, or brown components, or mixtures thereof thereby providing for the development and generation of black and/or colored images. The toner compositions of the present invention possess excellent admix characteristics as indicated herein, and maintain their triboelectric charging characteristics for an extended number of imaging cycles. The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic imaging and printing processes, including color processes.
Developer compositions with charge enhancing additives, which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of quaternary ammonium salts as charge control agents for electrostatic toner compositions. In this patent, there are disclosed quaternary ammonium compounds with four R substituents on the nitrogen atom, which substituents represent an aliphatic hydrocarbon group having 7 or less, and preferably about 3 to about 7 carbon atoms, including straight and branch chain aliphatic hydrocarbon atoms, and wherein X represents an anionic function including, according to this patent, a variety of conventional anionic moieties such as halides, phosphates, acetates, nitrates, benzoates, methylsulfates, perchloride, tetrafluoroborate, benzene sulfonate, and the like; U.S. Pat. No. 4,221,856 which discloses electrophotographic toners containing resin compatible quaternary ammonium compounds in which at least two R radicals are hydrocarbons having from 8 to about 22 carbon atoms, and each other R is a hydrogen or hydrocarbon radical with from 1 to about 8 carbon atoms, and A is an anion, for example, sulfate, sulfonate, nitrate, borate, chlorate, and the halogens such as iodide, chloride and bromide, reference the Abstract of the Disclosure and column 3 ; a similar teaching is presented in U.S. Pat. No. 4,312,933 which is a division of U.S. Pat. No. 4,291,111; and similar teachings are presented in U.S. Pat. No. 4,291,112 wherein A is an anion including, for example, sulfate, sulfonate, nitrate, borate, chlorate, and the halogens. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of electrostatic latent images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica.
Also, there is disclosed in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer compositions containing as charge enhancing additives organic sulfate and sulfonates, which additives can impart a positive charge to the toner composition. Further, there is disclosed in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with resin particles and pigment particles, and as charge enhancing additives alkyl pyridinium compounds. Additionally, other documents disclosing positively charged toner compositions with charge control additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014 and 4,394,430.
A patentability search report in a related copending application recited the following prior art, all U.S. Pat. No. 4,812,381 relating to toners and developers with quaternary ammonium salts of the formula illustrated in column 3, the preparation thereof, see column 4, and also note the working examples, columns 7 and 8, wherein specific charge additives, such as octadecyl ammonium trifluoromethane sulfonate, are reported; U.S. Pat. No. 4,675,118 which discloses certain quaternary salts as fabric softeners, see the Abstract of the Disclosure, and note column 1, for example, wherein X is as recited including OSO.sub.3 CH.sub.3 and halide; U.S. Pat. No. 4,752,550, the disclosure of which is totally incorporated herein by reference, directed to toners and developers with inner salt charge, see for example column 4; U.S. Pat. No. Re. 32,883 (a reissue of U.S. Pat. No. 4,338,390), the disclosures of which are totally incorporated herein by reference, wherein toners with organic sulfonate and organic sulfate charge enhancing additives are illustrated, see columns 3, 4, and 5 to 10 for example; and U.S. Pat. No. 4,058,585 which discloses a process of extracting metals with organic solvent solutions of the salts of hydrogen ionic exchange agents, and quaternary ammonium compounds including bisulfates. Processes for preparing quaternary ammonium salts by an ion exchange, or ion pair extraction method with soluble quaternary compounds is known, reference for example Phase Transfer Catalysis, Principles and Techniques, Academic Press, N.Y., 1978, especially page 76, C. M. Starks and C. Liotta, the disclosure of this textbook being totally incorporated herein by reference, and "Preparative Ion Pair Extraction", Apotekarsocieteten/Hassle, Lakemidel, pages 139 to 148, Sweden, 1974, which illustrates the preparation of certain bisulfates with water soluble ammonium salt reactants and a two-phase method wherein the product resides in the water phase.
Moreover, toner compositions with negative charge enhancing additives are known, reference for example U.S. Pat. Nos. 4,411,974 and 4,206,064, the disclosures of which are totally incorporated herein by reference. The '974 patent discloses negatively charged toner compositions comprised of resin particles, pigment particles, and as a charge enhancing additive ortho-halo phenyl carboxylic acids. Similarly, there are disclosed in the '064 patent toner compositions with chromium, cobalt, and nickel complexes of salicylic acid as negative charge enhancing additives.
There is illustrated in U.S. Pat. No. 4,404,271 a complex system for developing electrostatic images with a toner which contains a metal complex represented by the formula in column 2, for example, and wherein ME can be chromium, cobalt or iron. Additionally, other patents disclosing various metal containing azo dyestuff structures wherein the metal is chromium or cobalt include U.S. Pat. Nos. 2,891,939; 2,871,233; 2,891,938; 2,933,489; 4,053,462 and 4,314,937. Also, in U.S. Pat. No. 4,433,040, the disclosure of which is totally incorporated herein by reference, there are illustrated toner compositions with chromium and cobalt complexes of azo dyes as negative charge enhancing additives.
Other prior art includes Japanese Publication No. 54-145542 which illustrates a negatively chargeable toner consisting of a resin, a colorant, and the charge control agent pyridoxine aliphatic acid ester; East German Patent Publication 218697 relating to liquid developers with charge control additives with structural units of Formulas (I), (II) and (III), and which contains olefinically polymerizable bonds; U.S. Pat. No. 3,850,642 relating to multilayer sensitive elements with ionizable salts, acids, esters, and surfactants as charge control agents; U.S. Pat. No. 2,970,802 illustrating a composition for the control of hyperchloestermia, which composition consists of a nontoxic gelatin containing aluminum nicotinate; and U.S. Pat. No. 3,072,659 which discloses a method of preparing aluminum salts of nicotinic acid.
In copending application U.S. Pat. No. 4,937,157, the disclosure of which is totally incorporated herein by reference, there are illustrated toner compositions comprised of resin, pigment, or dye, and tetraalkyl, ammonium salts wherein alkyl, for example, contains from 1 to about 30 carbon atoms, ammonium bisulfate charge enhancing additives such as distearyl dimethyl ammonium bisulfate, tetramethyl ammonium bisulfate, tetraethyl ammonium bisulfate, tetrabutyl ammonium bisulfate, and preferably dimethyl dialkyl ammonium bisulfate compounds where the dialkyl radicals contain from about 10 to about 30 carbon atoms, and more preferably dialkyl radicals with from about 14 to about 22 carbon atoms, and the like. The aforementioned charge additives can be incorporated into the toner or may be present on the toner surface. Advantages of rapid admix, appropriate triboelectric characteristics, and the like are achieved with many of the toners of the aforementioned patent according to the disclosure thereof.
Preferred quaternary ammonium bisulfates disclosed in the aforementioned copending application are of the formula R'.sub.2 R".sub.2 N.sup.+ X.sup.- (R.sub.4 N).sup.+ X.sup.- wherein R' is aryl, substituted aryl such as alkylaryl, alkyl, preferably with 1 to about 30 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, heptyl, and preferably dimethyl dialkyl ammonium bisulfate compounds where the dialkyl radicals are from about 10 to about 30 carbon atoms, and more preferably dialkyl radicals with from about 14 to about 22 carbon atoms; R" is aryl, substituted aryl such as alkylaryl, alkyl, preferably containing from 1 to about 18 carbon atoms; and X.sup.- is a bisulfate (HSO.sub.4) anion.
Disclosed in copending application U.S. Ser. No. 396,497 , filed Aug. 21, 1989, is the compound distearyl dimethyl ammonium bisulfate and toner compositions thereof.
Disclosed in U.S. Pat. No. 4,904,762 , filed Aug. 21, 1989, is a toner composition comprised of resin, pigment, and a mixture of charge enhancing additives comprised of a first additive of quaternary ammonium salts and a second additive of an alkyl ammonium bisulfate.
Although many charge enhancing additives are known, there continues to be a need for toners with additives, which toners possess many of the advantages illustrated herein. Additionally, there is a need for positive charge enhancing additives which are useful for incorporation into black, and/or colored toner compositions. Moreover, there is a need for colored toner compositions containing certain charge enhancing additives. There is also a need for toner compositions with certain charge enhancing additives, which toners possess acceptable substantially stable triboelectric charging characteristics, and excellent admixing properties. Moreover, there continues to be a need for positively charged toner and developer compositions. Further, there is a need for toners with certain charge enhancing additives which can be easily and permanently dispersed into toner resin particles. There also is a need for positively charged black, and colored toner compositions that are useful for incorporation into various imaging processes, inclusive of color xerography, as illustrated in U.S. Pat. No. 4,078,929, the disclosure of which is totally incorporated herein by reference, laser printers, and additionally a need for toner compositions useful in imaging apparatuses having incorporated therein layered photoresponsive imaging members, such as the members illustrated in U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Also, there is a need for toner compositions which have the desired triboelectric charge level, for example, from about 10 to about 40 microcoulombs per gram, and preferably from about 10 to about 20 microcoulombs per gram, and admix charging rates of from about 5 to about 60 seconds, and preferably less than about 15 seconds, as determined by the charge spectrograph, preferably for example at low concentrations, that is for example less than 1 percent, and preferably less than about 0.5 percent of the charge enhancing additive of the present invention. It is believed that the sulfate anion of the charge additives of the present invention contributes to the desirable toner admix characteristics mentioned herein, and that the cationic segment influences the toner minimum fix temperature. Also, it is believed that the triboelectric charge of the toner is apparently more dependant on the cation segment. Further, the cation and anion segment together offer, it is believed, the capability to independently adjust or modify the toner triboelectric charge and admix by, for example, adjusting the amount selected. In admixtures with other charge additives, such as distearyldimethylammonium bisulfate, the ratio thereof can effect the toner triboelectric charge and admix characteristics independent of each other.